Fusion Message Board

In this space, visitors are invited to post any comments, questions, or skeptical observations about Philo T. Farnsworth's contributions to the field of Nuclear Fusion research.

Subject: Re: p + B11 reaction
Date: Feb 23, 11:00 am
Poster: Richard Hull

On Feb 23, 11:00 am, Richard Hull wrote:

>Ok, we've actually kicked this one around repeatedly. While Jim Lux is correct about both the low cross-section and the presence of neutron generating side reactions, he is incorrect about how incredibly useful the reaction is, because of two things: The neutronic side reactions are much lower in cross section than the main reaction, and the emitted alpha particles fit into tight energy bands. This second fact is the real advantage, b/c it means you can extract electrical power directly by decelerating those alphas through a 1.5 megavolt potential. This is much more efficient than the thermal energy extraction otherwise available.
>That said, the cross-section problem kicks it out of all but the most well-funded and powerful amateur fusors. According to http://silver.neep.wisc.edu/~neep602/lecture26.html, slide 26, the x-section for p-B11 reaction has an anomalous spike around 55 kV (anyone got an explanation for this?? I'm thinking it looks like an experimental error), higher than D-D at the same voltage, passes D-D for good at about 90 kV, and peaks around 200 kV, at which point it beats out D-T and D-He3 (which are both declining from their peaks at that point). In summary, I don't think it's worth it unless you are set up to go to at least 100 kV. I would look into putting your paws on some He3 instead, which peaks at about 100 kV, on par with D-T at the same voltage and way above everything else.

Well spoken indeed!!

This is good stuff! It is plain speak about the beauty of the theoretical possibilities with all the pros and cons of the P + B11 reaction and the suggestion of the He3 reaction being best of all for ultra high end amateur experimenter/fusorites.

The practicality for amateurs and limitations are layed out well. I think as new folks come on board, this topic will continued to be bounced around.

Those interested in the seemingly wonderful nirvana of "direct conversion" have been around in new cadres, wave after wave, since the 50's, it is not likely to abate as the energy crunch closes in on us. Fusion has lost a lot of its luster due to the ever present bureaucratic dawdling of politico-physics and phyicists since the 50's. Anyone who has followed the LLNL scandel on the massive laser IEC project over the last 8 months, must certainly be reduced to despair. It is sad. I have come to expect this kind of debacle from big science. In big science, one fails spectacularly. It is tough to just move on after such things, so the new thing is not to admit defeat but to either hand wave about unforeseen problems or enter into a round of finger pointing.

The P + B11 reaction carrot has not been plucked at for a reason by the big boys.(one would think) Any ideas? The theoretical musers and pundits, the amateurs and first glancers, all rave about it, seemingly to distraction.

I doubt any one on this board will take up the guantlet thrown down here due to expense and high end operation hassles, but I hope that if they do, we get a report on their results.

Richard Hull